JERUSALEM (Reuters) -- U.S. Vice President Joe Biden assured Israel today of Washington's commitment to its security and said the agreed resumption of Israeli-Palestinian talks provided a "moment of real opportunity" for peace.

Biden, who arrived on March 8, is the highest-ranking member of President Barack Obama's administration to visit Israel, where concern is high over Iran's nuclear program.

"There is absolutely no space between the United States and Israel in terms of Israel's security, our mutual security -- none at all," Biden said.

His visit coincided with Palestinian and Israeli agreement, in meetings with Obama's Middle East envoy George Mitchell this week, to resume peace talks suspended since December 2008, amid strong skepticism about their chances for success.

"I think we are at a moment of real opportunity," Biden said at a meeting with Israeli President Shimon Peres. He plans to see Palestinian leaders in the occupied West Bank on March 10.

"The interests of both the Palestinians and the Israeli people, if everyone would just step back and take a deep breath, are actually very much more in line than they are in opposition," he said.

But many Israelis seemed less interested in the peace talks with the Palestinians than in the messages Biden would convey about the confrontation over Iran's nuclear ambitions.

While saying he wanted direct negotiations with Palestinian President Mahmoud Abbas, Israeli Prime Minister Benjamin Netanyahu told American evangelical Christians in Jerusalem on March 8: "No security challenge is more important to our common future than preventing Iran from developing nuclear weapons."

Israeli political sources expect Biden to make clear, as other U.S. officials have done, that Obama wants no strike on Iran, notably by Israel, while Washington seeks to curb Tehran's nuclear program by means of sanctions. Netanyahu called again for tough sanctions to cripple Iran's trade in oil and gas.

"Since our administration came to power, I would point out that Iran is more isolated -- internally, externally -- has fewer friends in the world," Biden said.

In his remarks, Peres said: "We have trust in President Obama", and he called on Washington to "surround Iran with an envelope" to protect Israel against Tehran's "missiles and nuclear threat."

"Nobody knows exactly what they are doing," Peres said of Iran, which has denied it intends to make nuclear weapons.